Fixed dummy block for extrusion press



Feb. 14, 1967 STARR ET AL 3,303,684

XED DUMMY BLOCK FOR EXTRUSION PRESS Filed Dec. 9, 1963 5 Sheets-Sheet 1 \\W/// 70 6851 r 2 N z ,4 nu g: as \i 1; kg

FIG. I! 9a INVENTORS L y LEONARD RR 68 BY RICHARD YS --\w v I02 a arc d, i

ATTORNEYS F6314, 1967 STARR ETAL.

FIXED DUMMY BLOCK FOR EXTRUSION PRESS 3 Sheets-Sheet 2 Filed Dec. 9, 1963 INVENTORS LEONARD STA RR RICHARD HAYS ATTORNEYfi Feb. 14, 3967 L. STARR ET AL 3,303,684

FIXED DUMMY BLOCK FOR EXTRUSION PRESS Filed Dec. 9, 1963 5 Sheets-Sheet 3 {88 (S 26 94 u I4 INVENTORS LEONARD STARR BY RICHARD HAYS Mal/W ATTORNEYS United States Patent Ofi ice 3,303,684 Patented Feb. 14, 1967 Vania Filed Dec. 9, 1963, Ser. No. 328,851

' 4 Claims. (Cl. 72273) This invention relates to a fixed dummy block for extrusion press and more particularly to an improved device of this general class.

In the extruding of metals, a cast billet, generally cylindrical in shape, is heated to the desired extruding temperature and positioned in a press. The press includes an extrusion cylinder, and a ram which is fitted with a dummy block somewhat smaller than the cylinder diameter. The press also includes adjacent its forward end a die having an opening conforming to the cross-sectional configuration of the desired extrusion. As the ram moves forwardly against the dummy block, the pressure of the ram is transferred through the dummy block to the heated billet and the metal of the billet is caused to-flow or extrude through the die opening in a continuous rod having a cross-section substantially the same as the die.

In most extrusion presses heretofore used, the dummy block was loosely coupled to the ram with the aid of some type of Well known connecting means such as a pin that was loosely engaged in complementary openings in the forward surface of the ram and the rear surface of the dummy block. With such an arrangement the practice was to complete the extrusion of the billet to the extent possible, back-up the extrusion cylinder and ram, then shear the billet so as to separate most of it from the dummy block and the die, and then completely eject the dummy block and any portion of the billet adhering thereto. Thereafter, it was necessary for a workman to use a special tool to pick up the dummy block, severor remove the remaining portion of the billet therefrom and then replace the dummy block in its rearmost position immediately in front of the now Withdrawn ram.

It is to be noted that the dummy block not only functions to transfer the power of the ram to the billet, but it is also of a slightly smaller diameter than the internal diameter of the container. Thus, as the dummy block moves forwardly, it tends to leave a thin shell or coating of plastic metal on the internal surface of the container.

It has been determined that when a dummy block is fixedly coupled to the ram the dummy block will not only be moved forwardly by the ram, but will also be carried back rearwardly on the return stroke of the ram. However, it was found that the aforesaid thin coating of metal would be ironed rearwardly in excessive amounts on the return stroke thereby causing metal to collect behind the dummy block. This led to a failure of the press.

Furthermore, the press also jammed very quickly on the return stroke because of the tendency toward accumula* tion of metal for the reason previously stated, and also because on the return stroke the ram does not have the power that it possesses on the forward stroke.

It is therefore an object of the present invention to provide a fixed dummy block for extrusion press that will per form satisfactorily on the return stroke as well as on the forward stroke.

Yet another object of the present invention is to provide a fixed dummy block for extrusion press that will not cause jamming of the ram of the press on the return stroke.

Still another object of the present invention is to pro vide a fixed dummy block for extrusion press that will flex slightly on the forward stroke but will be of slightly smaller diameter on the return stroke, thereby avoiding the accumulation of the metallic material behind the dummy block.

Still another object of the present invention is to pro vide a fixed dummy block for extrusion press that will per mit the backward escape of heated entrapped air from the billet that is being extruded.

The foregoing objects as well as other objects of the in vention are achieved by providing a dummy block comprising a metal block having a concave forward surface, and a rear surface with a threaded internal opening that enables the dummy block to be coupled to the ram.

The outer surface of the dummy block tapers slightly outwardly in a forward direction. Thus, when the ram is on its forward stroke, the interaction of the hot billet and the dummy block concave forward surface causes the dummy block to flex slightly outwardly and thereby leave a thin plastic coating of aluminum on the container surface. However, on the return stroke the dummy block is not flexed and accordingly will be of a slightly smaller diameter. Therefore, on the return stroke, the dummy block will iron back any material projecting from the thin coating of metal on the container surface in a smooth manner and thereby avoid jamming or failure of the press.

The dummy block of the present invention also has a plug threaded into the central portion of its concave forward surface, the plug including a small exhaust port that communicates with the atmosphere and thereby permits the escape of entrapped air evolving from the billet.

Other objects and many of the attendant advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a perspective exploded view showing the dummy block of the present invention;

FIG. 2 is a sectional view showing the dummy block of FIG. 1 coupled to a ram and associated with a container assembly;

FIG. 3 is a view on a reduced scale showing the dummy block of FIG. 1 in. an extrusion press in retracted position with a billet in the container;

FIG. 4 is a view similar to FIG. 3 but wherein the ram is moving on its forward stroke and extruding metal from the die;

FIG. 5 is a sectional view on a reduced scale taken along the lines 5-5 of FIG. 2;

'FIG. 6 is a sectional view taken along the lines 6-6 of FIG. 2;

FIG. 7'is an enlarged view similar to FIG. 3 wherein the dummy block during its forward movement is making contact with the heated billet in the container, and also illustrating the escape of entrapped air through the exhaust port;

FIG. 8 is a greatly enlarged view of the upper portion of the dummy block demonstrating the tapered surface of the dummy block in relation to the internal surface of the container immediately prior to the making of contact between the dummy block and the billet;

FIG. 9 is a view similar to FIG. 8 but wherein the dummy block during its forward movement has made contact with the billet;

FIG. 10 is a view on a reduced scale similar to FIG. 9 showing the ironing of the metallic coating on the forward stroke of the dummy block; and

FIG. 11 is a view similar to FIG. 10 but taken during the return movement of the dummy block.

Referring now in greater detail to the various figures of the drawings wherein similar reference characters refer to similar parts, there is generally shown in FIG. 1 at 10 a fixed dummy block constituting an embodiment of the present invention.

The dummy block basically comprises a metal block 12 including a forward concave surface 14 and a rear surface 16. A plug 18 is associated with the forward surface 14 and a connecting pin 20 is associated with the rear surface 16.

In use the dummy block 10 is inserted in a container 22 (FIG. 2) in order to be urged forwardly by the ram 24 in order to act upon the hot billet 26 and thereby extrude metal through the die 28.

The usual elements of an extrusion press in association with the present invention are illustrated in FIGS. 3 and 4. The container 22 is arranged in a container holder 30 slidably mounted for axial movement on a frame 32. The container 22 has an axial extending opening 34, in which the billet 26 to be extruded is positioned.

At the discharge end of opening 34 there is positioned a die means 28 with die ring 36 through which the material of the billet 26 is to be pressed. The die 28 is supported in the die ring 36 and in the die holder means 38 on a platen 40.

In order to extrude the material through the die 28, there is provided a main ram 42 adapted to be operated out of'a main cylinder 44 by fluid pressure supplied from an accumulator (not shown). Attached to the main ram 44 is an extension piece generally indicated at 46 which has portions 48, 50 of reduced diameters. Extension piece 46 is connected to a main crosshead 52 movable with the ram, the crosshead 52 being slidably supported on the frame 32.

The press of FIG. 3 also includes an auxiliary crosshead 54 from which the ram 24 depends. Rods 56 are provided which determine the length of the forward stroke of the press. As further shown in FIG. 3 the press includes a slidable crosshead 58 having shoes (not shown) sliding on rails formed at the lower ends of a bracket 60 fixed on tie rods 62 of the frame 32.

Attention is again referred to FIG. 1 and in particular to the metal block 12 of the dummy block 10. As shown in FIG. 1 the metal block 12 essentially comprises a rear section 64 of essentially constant cross-section and a forward section 66 which tapers outwardly forwardly in a taper 68 as indicated in considerable detail in FIGS. 7 to 11. The taper 68 terminates forwardly in a collar 70, and for instance may be a 3 taper outwardly from the rear section 64. However, the precise amount of taper will vary somewhat as will be readily apparent to those skilled in the art depending upon the dimensions of the dummy block and the container and the operating temperature. In a specific embodiment of the invention the 3 taper extended for a substantial portion of the dummy block outer surface of approximately two inches.

Attention is further referred to forward concave surface 14 of the dummy block as best shown in FIG. 2 The concavesurface 14 may take the form of an arc of a circle of, for instance a 3%. inch radius and as shown in FIG. 1 has a threaded central opening 72 formed therein. The threaded opening 72 receives the plug 18 which has threads complementary to those defining the opening 72. I

The details of the plug 18 are best shown in FIG. 7 and as there shown the forward surface 74 of the plug includes a concave section 76 defined by inclined edges 78 and central section 80 having exhaust port 82 formed therein. The exhaust port 82 is of an extremely small diameter of the order of 0.010 inch to avoid entry of hot metal therein. As further shown in FIG. 7 the exhaust port 82 communicates with a larger opening 84 in the plug 18 that is co-extensive with passageways 86 and 88 in the dummy block which lead to the atmosphere.

It is to be noted that the forward section of the dummy block is essentially concave as defined by the concave surface 14 and the concave section 76 of the plug 18. The purpose of the concave configuration is to assist in tge fleifring of the dummy block during the forward stroke t ereo little resistance on the return stroke.

However, the rear surface 16 of the dummy block is generally flat and is secured to the forward surface of the ram 24 by means of the threaded connecting pin 20 as illustrated in FIGS. 2 and 7.

Finally, as shown in FIG. 2 both the dummy block and the plug includes taps 90 for purposes of permitting the insertion of a tool to aid in the threading together or separating of the respective parts.

The general operation of the extrusion press may be observed by comparing FIGS. 3 and 4. As shown in FIG. 4 the ram 24 has moved forwardly so that the dummy block is urging the hot billet 26 through the die 28 thereby creating extrusion 92.

During the forward stroke of the ram the function of the taper 68 may be particularly observed by studying FIGS. 8, 9 and 10. FIG. 8 shows the condition of the dummy block immediately before it contacts the hot billet 26. As shown in FIG. 8 a slight clearance 92 exists between the collar 70 and the inner surface of the container 22. As the dummy block 10 is moved forwardly in the direction of arrow 94, the dummy block 10 comes in contact with the hot billet 26. Because of the flow resistance occasioned by the abutment of the billet 26 against wall 96, the dummy block tends to oppose the forward motion of the ram 24.

Because of the concavity of forward surface 14, the collar 70 of the dummy block (FIG. 9) is actually caused to flex slightly outwardly so as to come closer to the inner surface of the container 22. This is shown in more detail in FIG. 10 wherein the inner surface of the container 22 is shown .to have a thin plastic coating 98 of metal formed thereon. This coating of metal 98 has been applied or left during the course of previous extrusion made by the press and as a practical matter cannot be eliminated although it is quite thin.

As shown in FIG. 10 the flexing of the collar 70 of the dummy block has the effect of leaving a metallic layer 98 in the form of a thin shell 100. In this connection it is believed that the collar 70 is flexed on the forward stroke to an extent of 0.005 inch. However, this is sufficient to achieve the ironing back effect on the return stroke of the press.

The return stroke of the dummy block in the direction of arrow 102 is illustrated in FIG. 11. Here, there is no interaction between the billet and the concave surface 14 of the dummy block, and hence the collar 70 is not flexed on the return stroke. This permits the taper 68 to interact with the inner skin plastic layer 98 to iron the same gently rearwardly in mass 104, and hence there is It is to be noted that the present dummy block has been dimensioned to be usable with aluminum in the operating temperature of 600 F. to 1,000 F.

During the forward stroke of the dummy block any entrapped air may escape through the exhaust port 82. When the forward stroke has been completed the remaining portion of the billet 26 may be separated from the concave surface 14 and the concave section 76 of the plug 18 by virtue of an outward force being applied to the remainder of billet 26. Well known lubricants may be used to effect the separation.

It is thus seen that by virtue of the concavity of the dummy block forward surface, it will flex slightly on the forward stroke, and on the return stroke the plastic layer on the container wall will be ironed smoothly, thereby avoiding interference with extrusion press operation.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed as the invention is:

1. A dummy block movable within a container of an extrusion press, said container having a generally cylindrical inner surface, said dummy block being used in forwardly extruding a metal billet and being adapted to be urged in a forward direction against said billet by the forward stroke of a ram and to be returned to a rearward position by the rearward stroke of said ram to which said dummy block is attached, said dummy block comprising a metal block having a concave forward surface adapted to contact said billet and a rear surface adapted to be contacted by said ram, an exhaust port in said concave forward surface connecting to the atmosphere, said dummy block also having an outer surface extending between said forward and rear surfaces, said dummy block outer surface being of a diameter somewhat smaller than the diameter of the inner surface of said container, a substantial portion of said dummy block outer surface between said rear and forward surfaces tapering slightly outwardly in a forward diection and also toward the inner surface of said lCOl'ltZllIlBI', whereby when said dummy block is urged in a forward direction against said billet, the interaction of the dummy block concave forward surface with said billet causes the out wardly tapering outer surface of said dummy block to fiex somewhat outwardly and toward said container inner surface to provide on the forward stroke a somewhat deep penetration into said billet, leaving a plastic metallic coating upon said container inner surface, but said dummy block will not be so fiexed on the rearward stroke, with said tapering outer surface thereby on the rearward stroke smoothly ironing back said plastic metallic coating and eliminating the ironing back of excessive amounts of said metallic coating to greatly reduce the power required to return the dummy block to its rearmost position and to substantially eliminate fouling of the dummy block on the return stroke.

2. The invention of claim 1 wherein said forward surface includes a threaded bore in which a threaded plug is inserted, said plug having an extremely small exhaust port connected to the atmosphere.

3. The invention of claim 1 wherein said outer surface terminates in a collar adjacent said forward surface.

4. The invention of claim 1 wherein a threaded pin connects said dummy block and ram.

References Cited by the Examiner UNITED STATES PATENTS 927,076 7/1909 Remmen 72255 1,330,489 2/1920 Reuberth 72273 2,904,830 9/1959 Mulrooney 72-273 2,925,176 2/1960 Wyngaert 72273 FOREIGN PATENTS 192,471 12/1907 Germany. 528,137 3/1930 Germany.

CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner. 

1. A DUMMY BLOCK MOVABLE WITHIN A CONTAINER OF AN EXTRUSION PRESS, SAID CONTAINER HAVING A GENERALLY CYLINDRICAL INNER SURFACE, SAID DUMMY BLOCK BEING USED IN FORWARDLY EXTRUDING A METAL BILLET AND BEING ADAPTED TO BE URGED IN A FORWARD DIRECTION AGAINST SAID BILLET BY THE FORWARD STROKE OF A RAM AND TO BE RETURNED TO A REARWARD POSITION BY THE REARWARD STROKE OF SAID RAM TO WHICH SAID DUMMY BLOCK IS ATTACHED, SAID DUMMY BLOCK COMPRISING A METAL BLOCK HAVING A CONCAVE FORWARD SURFACE ADAPTED TO CONTACT SAID BILLET AND A REAR SURFACE ADAPTED TO BE CONTACTED BY SAID RAM, AN EXHAUST PORT IN SAID CONCAVE FORWARD SURFACE CONNECTING TO THE ATMOSPHERE, SAID DUMMY BLOCK ALSO HAVING AN OUTER SURFACE EXTENDING BETWEEN SAID FORWARD AND REAR SURFACES, SAID DUMMY BLOCK OUTER SURFACE BEING OF A DIAMETER SOMEWHAT SMALLER THAN THE DIAMETER OF THE INNER SURFACE OF SAID CONTAINER, A SUBSTANTIAL PORTION OF SAID DUMMY BLOCK OUTER SURFACE BETWEEN SAID REAR AND FORWARD SURFACES TAPERING SLIGHTLY OUTWARDLY IN A FORWARD DIRECTION AND 